Modern seat belts comprise a length of webbing arranged to pass diagonally across the torso, and generally horizontally across the hip region of the vehicle occupant (so-called lap portion of the belt). This is known as a three-point belt system. One end of the belt webbing is firmly attached to a structural part of the vehicle such as the floor, and the other end is attached to the spool of a retractor which itself is firmly attached to a structural part of the vehicle, usually the side B-pillar. Between the retractor and the fixed point, a fastening element such as a metal tongue is fixed to the belt with which it can be fastened into a buckle which itself is attached to fixed part of the vehicle on the other side of the occupant seat to the retractor.